It was proven by Shannon that the separation of source and channel coding is without loss of optimality when the blocklength goes to infinity [1]}.
Nevertheless, in practical applications we are limited to finite blocklengths, and it is known that combining the two coding steps, that is, joint source-channel coding (JSCC), can achieve lower distortion for a given finite blocklength than separate source and channel coding [2]}, [3]}, [4]}.
The most straightforward approach to JSCC is to optimize the various parameters between source coding, channel coding and modulation in a cross-layer framework.
Although many such schemes have been proposed over the years [5]}, [6]}, [7]}, none were able to provide sufficient gains to justify the increased complexity.
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